Tube-expanding device



Jan. 13, 1931. R. N. TRAVNE 1,788,474

TUBE EXPANDING DEVICE Original Filed April 23, 1926 .Reabezz fi lfiwiza Pat nted Jan.-13, 1931 UNITED STATES PATENT OFFICE REUBEN n. TBANE, or LA cnossn, wrsconsm TUBE-EXPANDING DEVICE Original application filed April as, 1926, Serial No. 104,196. Ibi'vided and this application filed May a1,

1928. Serial No. 282,001.

This invention relates to a tube expanding device and it pertains more particularly to a device for expanding radiator tubes against the reinforced flanges of heat-radiating fins. This application'is a division of my copending applicationSerial No. 104,196, filed April 23, 1926.

' An object "of this invention is to simplify similar parts throughout the several views the same referencepharacters being used as. were employed in the parent application above cited) Fig. 1 is a perspective view of one of the 2 heat-radiating fins;

Fig. 2 is a perspective view of one form of a stamped, forged, or spun-metal spacing ring used in conjunction with the fin shown in Fig. 1;

Fig. '3 is a fragmentary transverse vertical section on an exaggerated scale of one of the radiator heat tubes showing the method of holding the fins in heat-conducting contact therewith and showing the improved apparatus for expanding the tube to complete the contact;

' Fig. 4 is a side elevation of a machine for expanding the heat tube according to the method shown in Fig. 3; p Fig. 5 shows an alternative'form of heatradiating fins F where the margins of the openings in the fins are. spun or drawn into refolded flanges which inter-nest; and

Fig. 6 is a plan view of the tube T on a reduced scale with the fins'removed.-

The fins F shown in Fig. 1 are adapted to be mounted in heat exchange relation on a tube T (Fig. 3); This assembly is used as a radiator unit in substitution for the usual cast-iron radiator. It afl'ords a certain which this application isa division.

.In order to keep the" radiator as light as possible, I prefer to use very thin metal for the fins. Sheet copper .007 inches thick has been found to give verysatisfactory resultsand 1 a minimum weight. Obviously the flanges f struck from such sheets will not have enough strength to form and maintain a good heat-cbnducting contact with the outer surface of a tube T; and also the flanges are neither strong enough nor thick enough to serve as spacers between adjacent fins with out danger of the flanges overlapping or bein crimped.

o overcome spacing rings or ferrules R which are disposed as sleeves about the outer peripheries of the flanges f and with'the faces of the rings abutting the opposed faces of adjacent fins F. These spacing rings not only serve as relative unyielding sleeves between which and the tubes the flanges fmay be tightly and permanently compressed to preserve a firm heat-conducting contact over a lar e area between the fins and the tubes, but a so supplement the heat conduction by reason of the contact between the faces of the rings and the flanges of the fins thereby serving much as hubs to augment the cross-sectional area of heat conduction where the heat conduction must necessarily be the most concentratedin its path from the tube to the radiating surfaces of the fins.

In order to avoid any complications from varying coefiicients of expansion, I make the tubes T, the fins F and the spacing rin s R these difiiculties, I provide all of copper-"and, at least in those met ods of assembly wherein I expand the tube in order to press the tube and fin tightly against each other and against the spacing ring, I- prefer to maintain a proportion between the thicknesses ofthethree elements somewhat f as follows: The fins areformed from sheet stock .007 inches thick, the shell of the tube T is about .020 inches thick and the spacing rings .are stamped from stock about .030 inches thick. Instead of forming rings of rectangular cross-section, as by cuttin them from tubing, I refer, for the sake o economy, to stamp t e spacing rings from sheet metal, and I have found that in stamping them the most satisfactory form, from-the viewpoint of production, is a channel-shaped section where one flange of the channel is longer than the other, as this does not necessitate drawing the metal so much as it would if the flanges were equal.

In any case, whether the rings be rectangular or channel-shaped or whether other reinforcing means are provided, I have found that to obtain the most satisfactor results it is necessary for the flanges f of t e fins F to be permanently pinched between the tube and the reinforcing members so that these elements become in effect an integral metallic path for the conduction of heat.

My preferred embodimentthe one I have founimpst effectiveis illustrated in Fig. 3. The fins are placed in position on the tubes,

the spacing rings R between adjacent fins and with the parts fitting rather snugly and compressed lon 'tudinally on the tubes to their final position. Thetube is then externally expanded against the relatively unyielding rings R with the result that by the expansion of the tube the flanges f of the fins are permanently pinched into firm heat-conducting contact with the tube and with the spacing rings, while the flanges of the spacing rings are held permanently in firm heatconducting contact with the faces of the fins about the margins of their flanged openings.

I prefer to effect this internal expansion of the tube by means of a rotary mandrel or spindle having threads 25 thereon such as is I shown in detail in Fig. 3. In this method the assembled radiator unit, which consists of the U-shaped tube T with the fins-and rings inposition upon it and held longitudinally compressed by a clamping frame 45 as shown in Fig. 4, is moved on a carriage 46 along the bed of an expanding machine to project the rotary mandrel 47 through the interior of one leg of the tube. If desired two spaced mandrels 4.7 may be employed so that the expanding operation is performed simultaneously in both legs of the tube T.

An arbor 48 projects outwardly from the interior of a head 49 at the end of the mandrel 47, the arbor being .tapered toward its end and carrying a bushing 50 having a similarly tapered bore but a cylindrical periphery. The bushing 50 is obliquely cut or slotted, as indicated at 51, to form a split bushing. A set of four rollers 52 trunnioned at their ends to engage radial slots 53 in head 49. The overall diameter to which the rollers 52 will expand the bore of thetube T is adjusted by pulling the split bushing 50 farther onto the tapered arbor 48 by a nut 54 at the end of the arbor which nut also locks the bushing in any adjusted position. The forward ends of the rollers 52 are slightly chamfered or rounded to facilitatetheir action in expanding the bore of the tube T as the rotating mandrel is pushed into the tube. The nut 54 is preferably so adjusted that the tube T will be expanded to as great a diameter as possible without breaking or materially deforming the spacing rings R but still permanently pinching the flanges f as previously described.

For my heat tube I prefer to use a tube which has been externally coated with tin or solder, as by dipping. After the tube has been expanded the tube is heated to the melting point of the tin either by placing the entire unit within an oven or by passing a flame through the tube. The melted tin or solder completely fills any minute spaces there may be between the flanges f and the tube. This method may be usedeither to supplement the expanding or other alternative methods herein described, or alone if the flanges and spacing rings fit comparatively snugly on the tu e.

While I have described a preferred embodiment of my invention, it is understood that I am not limited to the details therein set forth except as defined by the following claims.

I claim:

1. In a device for expanding a metal radiaa similarly tapered bore and a cylindrical periphery and having a diagonal slot in one side, means for moving said bushing longitudinally along said arbor, and means carried by said bushing for coacting with and expanding the metal tube.

2. In a device for expanding a metal radiator tube, a mandrel provided with a tapered arbor, a slotted bushing provided with a similarly tapered aperture and with a cylindrical circumference, rollers carried by said bushing and adapted to bearagainst and expand the metal tube, and means for locking said bushing at various longitudinal ositions on said arbor whereby the degree of expansion of said tube may be regulated.-

3. In a device of the class described, a rotary spindle, a tapered arbor thereon,'a slotted bushing provided with a similarly tapered aperture and a cylindrical periphery,

rollers with beveled ends carried by said bushing, and means for expanding said bushing and for locking it in expanded position. 4. In a device of the class described, a threaded spindle, a tapered arbor on the end thereof, a slotted bushing having an aperture therein, said bushing being tapered internally to co-act with the taper on the arbor, a plurality of rollers carried by said bushing, means threaded on'said spindle and longitudinally confining said rollers, said rollers being forced outwardly to expand the tube by longitudinal movement of the bushin' on the arbor, and means for locking the bus ing in fixed position on said shaft.

5. In a device for expanding a metal radiator tube, a rotary spindle, a tapered arbor thereon, a bushing on said arbor having a similarly tapered bore and a cylindrical periphery and having a diagonal slot in one side, means for moving said bushing longitudinally along said arbor for expanding said bushing, and adapted to lock the bushlng at various longitudinal positions on said arbor,

rollers engaging the cylindrical surface of said bushing for co-acting with and expanding the metaltube, and means adjacent the ends of said rollers for limiting the radial movement thereof.

In witness whereof, I hereunto subscribe my name this 24 day of May, 1928.

REUBEN N. TRANE. 

